2 Answers
2

There is no reason why anyone should write a MySQL based editor.
Your best chance to archive this is to find a greedy and/or lunatic programmer that will write you a MySQL-virtual drive.
Yes this IS possible, and at least on windows it does not take much skills.

Well, you could use one of the existing php online editors, and hack the Horde VFS backend in, allowing you to read local files or a database file storage. Another alternative was writing your own FUSE driver. Most sensible however would be to make your database contents available over WebDAV, allowing you to use Eclipse or so